wc -l medals.txt
grep -E "中国|中国香港|中国台北" medals.txt | sort -t "," -k2nr -k3nr -k4nr
sort -t "," -k4nr medals.txt | head -n 5 | cut -d "," -f1
sort -t "," -k2nr medals.txt | head -n 5 | awk -F "," "{sum+=\$2} END{print \"金牌总数：\"sum}"
